O -(2-[ 18 F]Fluoroethyl)- l -tyrosine and l -[methyl- 11 C]methionine uptake in brain tumours: initial results of a comparative study

Abstract

O-(2-[18F]Fluoroethyl)-L-tyrosine (FET) is a recently described amino acid analogue that has shown high accumulation in animal tumours. The aim of this study was to compare the uptake of FET with that of L-[methyl-11C]methionine (MET) in patients with suspected primary or recurrent intracerebral tumours. Sixteen consecutive patients with intracerebral lesions were studied on the same day by positron emission tomography (PET) using MET and FET. Uptake of FET and MET was quantified by standardized uptake values. Tracer kinetics for normal brain and intracerebral lesions were compared. On the basis of the MET-PET studies, viable tumour tissue was found in 13 patients. All tumours showed rapid uptake of FET and were visualized with high contrast. Mean uptake of FET for normal grey matter, white matter and tumour tissue was 1.1+/-0.2, 0.8+/-0.2 and 2.7+/-0.8 SUV, respectively. In all three tissues, uptake of MET was slightly higher (1.4+/-0.2, 0.9+/-0.1 and 3.3+/-1.0 SUV; P<0.01). However, contrast between tumour and normal tissues was not significantly different between MET and FET. Uptake of FET in non-neoplastic lesions (1.0+/-0.1 SUV) was significantly lower than in tumour tissue (P = 0.007). For all lesions there was a close correlation (r = 0.98) between MET and FET uptake. In conclusion, in PET studies of human brain tumours, the uptake and image contrast of FET appear to be very similar to those of MET. The specificity of FET for tumour tissue is promising but has to be addressed in a larger series of patients with non-neoplastic lesions.

Delineation of Brain Tumor Extent with [11C]l-Methionine Positron Emission Tomography

“…[ 11 C]MET is incorporated into most brain tumors, even into low-grade gliomas, and is being used in the management of patients with gliomas (8,9). [ 11 C]MET is a sensitive tracer in tumor detection, and it differentiates benign from malignant lesions with high sensitivity and specificity with relatively low background activity in normal brain tissue (5,10).…”

18 F-choline in experimental soft tissue infection assessed with autoradiography and high-resolution PET

“…One is the reduced specificity for tumour cells due to FDG uptake in inflammatory lesions. A promising candidate for higher tumour specificity was 18 F-ethyl tyrosine (FET), which does not accumulate in inflammatory lesions [1] and which had shown promising potential in the evaluation of brain tumour patients [2]. Unfortunately, FET proved to be less sensitive than FDG in whole-body imaging of certain tumours [3].…”

Novel Quantitative Techniques in Hybrid (PET-MR) Imaging of Brain Tumors

“…MET-PET and FET-PET have shown to have similar tumor uptake patterns. 56 AA-PET has been gaining interest and is routinely being performed to differentiate viable tumor form radiation-induced necrotic regions. In GTV delineation, AA-PET is used to determine tumor extent.…”